Implement journald exporter for OpenTelemetry #84
Conversation
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@TommyCpp had an question on comparing it with the subscriber provided by Tokio tracing library - https://github.com/tokio-rs/tracing/blob/master/tracing-journald/ -
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comment the json_format option.
This was motivated by the improved downstream developer experience from being pure Rust, and the simplicity of the journald client protocol. It's not significantly more complicated than FFIing to libsystemd, and it dramatically reduces the sensitivity of downstream crates to build environment issues like missing pkg-config files, linking during cross-compilation, etc. |
Thanks, @Ralith, for the background. The concerns regarding build complexities with FFI to C are valid, and we will consider documenting this for the developers. My motivation for using libsystemd is that it internally handles sending large data through memfd, and so abstracting these low-level details. And hopefully being future-proof with any protocol changes :) |
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| pub fn attribute_prefix(mut self, attribute_prefix: Option<String>) -> Self { |
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It would be more user friendly to just ask them for a string slice instead of having them to call to_string() and wrapping it with an Option.
| pub fn attribute_prefix(mut self, attribute_prefix: Option<String>) -> Self { | |
| pub fn attribute_prefix(mut self, attribute_prefix: &str) -> Self { |
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| pub fn message_size_limit(mut self, message_size_limit: usize) -> Self { | ||
| self.message_size_limit = Some(message_size_limit); |
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Add some validation? Something like message_size_limit > 0?
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| #[cfg(not(feature = "json"))] | ||
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| return Err(std::io::Error::new( |
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Move this validation to json_format method where the user configures this bool variable instead of checking it in export method?
| let identifier = self.identifier.ok_or("Identifier is required")?; | ||
| let message_size_limit = self | ||
| .message_size_limit | ||
| .ok_or("Message size limit is required")?; |
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Could we have a default value for message_size_limit instead of requiring the user to always specify this?
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Yes, default is 0 now, which means no limit is enforced.
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| pub fn build(self) -> Result<JournaldLogExporter, &'static str> { |
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Could we simply return JournadLogExporter instead of a Result?
| pub fn build(self) -> Result<JournaldLogExporter, &'static str> { | |
| pub fn build(self) -> JournaldLogExporter { |
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| fn init_logger() -> LoggerProvider { | ||
| let exporter = JournaldLogExporter::builder() | ||
| .identifier("opentelemetry-journal-exporter") |
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Assign with prefix to the builder methods?
| .identifier("opentelemetry-journal-exporter") | ||
| .message_size_limit(4 * 1024) | ||
| .attribute_prefix(Some("OTEL_".to_string())) | ||
| .json_format(true) //uncomment to log in json format |
Changes
This adds
Journaldlog exporter for OpenTelemetry, allowing logs to be sent to Journald. Note that this exporter is experimental, and breaking changes are expected. The performance and stability improvements are required, and contributions are welcome.Features:
memfdcan be used for sending large messages.Dependencies:
This implementation relies on the
libsystemdlibrary for sending log entries to the journald daemon. It usessd_journal_sendvAPI method provided by the library.Merge requirement checklist
CHANGELOG.mdfiles updated for non-trivial, user-facing changes